Potentiometer equipped with positive positioning means

ABSTRACT

A variable resistor for regulating flow of electrical energy in an electrical circuit including a contact member with means for moving same over a resistance element wherein releasable securing means are provided for assuring a predetermined positioning of the contact member relative to the resistance element.

United States Patent De Long et al.

[ 51 Mar. 7, 1972 POTENTIOMETER EQUIPPED WITH POSITIVE POSITIONING MEANS lnventors: Robert J. De Long, Temple City; Paul F.

Gerwitz, West Covina, both of Calif.

Assignee: Spectrol Electronics Corporation, City of Industry, Calif.

Filed: May 6, 1970 Appl. No.: 37,374

Related US. Application Data Continuation of Ser. No. 741,144, June 28, 1968, abandoned.

US. Cl ..338/l43, 338/ 149 Int. Cl r ..Hlc /00 Field of Search .L ..338/l43, 149, 202

Primary Examiner-Thomas J. Kozma Attorney-Herman Seid and Harry G. Martin, Jr.

[5 7] ABSTRACT A variable resistor for regulating flow of electrical energy in an electrical circuit including a contact member with means for moving same over a resistance element wherein releasable securing means are provided for assuring a predetermined positioning of the contact member relative to the resistance element.

3 Claims, 2 Drawing Figures 10 ll 46 n 1 will H e9. I l 2 2 14 PAIENTEQMAR 7 1972 3,54 ,217,

FIG. I

50 32 I 4| T l \24 i 45 Q 44 I5 46 I 2 FIG 62 5 4a WWI,"

ATTORNEY.

POTENTIOMETER EQUIPPED WITII POSITIVE POSITIONING MEANS This application is a continuation of application Ser. No. 74 l l 44, filed June 28, I968, now abandoned.

BACKGROUND OF THE INVENTION This invention is concerned with a variable resistor of the kind employed in electric circuits for the purpose of varying the flow of electrical energy within the circuit. Devices of the kind described include a resistance element, a contact member arranged for slidable engagement with the resistance element and a shaft or. the like for providing movement to the contact member.

In certain applications, it is important that the contact member be maintained stationary relative to the resistance element as a predetermined setting.

The chief object of this invention is the provision of locking means for releasably securing the contact member in a predetermined position in a resistor of the kind described.

SUMMARY OF THE INVENTION The invention involves utilization of spring-actuated plunger means in the form of a ball bearing adapted to be received in a detent formed in the slider block employed for the purpose of supporting the contact member during its movement along the resistance element.

The slider block, in addition to incorporating the detent as described, has provided on the surface of the slider block adjacent the detent inclined sections which permit the slider block to be engaged with and disengaged from the plunger with the application of a relatively small amount of torque applied to the slider block through an actuating membersuch as a shaft.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is an elevational view in section of a variable resistor incorporating the locking means forming the subject of this invention; and I FIG. 2 is a view in section taken along lines IIII of FIG. 1 illustrating the cooperation between the slider block and locking means.

DESCRIPTION OF'THE PREFERRED EMBODIMENT A variable resistor is shown in FIGS. 1 and 2 and is commonly known in the art as a potentiometer inasmuch as the resistor is adapted for use in precision instruments employed in intricate control systems. The resistor shown is a common form known as a multiturn potentiometer and will be easily recognized by those skilled in the art. I

The variable resistor 10 includes a housing composed of a cylindrical body 13 together with end covers 14 and 16 arranged to form an enclosure for the various operating parts of the resistor. It will be appreciated that appropriate fastening members, such as clamp bandslS, may be employed for connecting the end covers to the body portion. The parts forming the housing are preferably made from molded plastic material.

Arranged within the housing 13 is a resistance element I7 coiled so as to assume a helical configuration. The resistance element includes a support member around which a relatively fine wire is helically wrapped prior to coiling the assembly to the configuration shown. Appropriate insulation is applied to the mandrel and .wires as is also known in the art. A shaft 20 is arranged centrally of the housing and is supported in bearings 22 carried by the, covers 14 and 16.

A slider block 24 is provided within an axial groove 25 formed in an enlarged section 26 of shaft 20. A key 27 is formed on the undersurface of slider block 24 and cooperates with groove 25 to confine relative movement between the slider and shaftto an axial path.

Assembled within slider block 24 is a contact-supporting insert 28 including a radial fin portion 30. integrally formed therewith. The insert 28 is secured in transverse groove 32 formed in the-block 24. Attached to the lower surface 34 of a transverse groove 36 in the insert 28 is a contact member 38 having a configuration as indicated in FIG. 2. The parts are arranged. so that the free end of the contact member will yieldably bear against the resistance member when assembled as shown in FIG. 2. The opposite end of the contact member is connected to a flexible lead 40 in turn connected to a metallic bar. 41 secured to a metallic ferrule 42 encircling a sleeve 44 formed of electrically insulating material fixedly secured to the shaft 20. The ferrule 42 acts in the manner of a slipring having continuous engagement with a free end of conductor 45 secured to terminal 46 mountedto the housing 13.

Arranged within an opening 48 extending radially through the body 13 is a releasable locking means 50 comprising an externally threaded hollow member 52 enclosing a spring-urged ball 54 acting as a locking plunger. Slider block 24 is provided with a depression or detent 58 having opposed sloping surfaces 60 and 62 extending therefrom.

Considering the operation of the variable resistor equipped with the releasable locking means 50, it will be appreciated that rotary movement applied to the shaft will cause the slider block to rotate and longitudinally advance in the manner of a leadscrew as fin 30 engages the side of the resistance element 17 with the end of the contact member 38 bearing against the resistance element. The position of the contact on the element will determine the potential across one of the terminalsconnected to the resistance element and the terminal connected to the conductor 45.

As the contact member approaches the end of its path of travel over the inner surface of the coiled resistance element, sloped surface 60 will engage the ball 54 causing it to be" forced upwardly against its mounting spring into the hollow member 52. Eventually the slider will move to a position where detent 58 is in registry with the ball 54. Through the action of its mounting spring, ball 54 will be forced downwardly into locking engagement with the depression rendering the slider block fixed relative to the resistance element.

When it is desired to actuate the contact member to vary the output of the resistor, a relatively small amount of torque will cause disengagement of the ball 54 and depression 58 allowing relative movement therebetween.

While we have described a preferred embodiment of the invention, it is to be understood the invention is not limited thereto since it may be otherwise embodied within the scope of the following claims.

We claim:

1. In a multi-turn variable resistor including a helically formed resistance element, a housing supporting the element about the inner surface thereof, shaft means located within said housing, a slider block carried by said shaft means, electrical conductor means supported by said housing in engagement with spaced positions on said element,

a contact member supported by said slider block and adapted to slidably engage the resistance element in response to rotary movement of said shaft and means for releasably securing the slider block relative to said resistance element at a predetermined position of the contact member within the housing.

2. A variable resistor as set forth in claim I wherein said slider block includes a detent formed in the surface for engagement with said yieldably mounted element to retain the slider block in fixed position relative to the housing.

3. In a multiturn variable resistor including a helically formed resistance element, a housing supporting the element about its inner surface thereof, shaft means located within said housing, a slider block carried by said shaft, electrical conductor means supported by said housing in engagement with spaced positions on said element,

a contact member supported by said slider block and adapted to slidably engage the resistance element in response to rotary movement of said shaft and yieldable means for releasably securing the slider block relative to said resistance element at a predetermined position of the contact member within the housing, said yieldable means being arranged within a radial opening formed in the surface of the housing accommodating the helically formed resistance element so that the end thereof projects into the path of travel of the slider block. 5

I i I! 4 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 6 8, 217 Dated March 7, 197

lnventofls) ROBERT J. DE LONG 86 PAUL F. GERWITZ It is certified that .error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 17, "as should read at-- Column '2', line 5?, Claim 1, after "means" insert ineluding a yieldabl'y mounted element disposed in said housing-- Signed and sealed this l2th day of December 1972.

(SEAL) Attest:

Attes'ting Officer ROBERT GOTTSCHALK Commissioner of Patents use-1050 v( 69) V I USCOMM-DC 60376-P69 fi US. GOVERNMENT PRINTING OFFICE: 1959 O-366-334 UNHTED STATES PATENT OFFICE EENWCATE OF C.ETEN

Patent NO. -3,6 +8,217 Dated March 7, 1972 I Inventofl) ROBERT J. DE LONG 86 PAUL F. GERWITZ It is certified that verror appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line l7, as should read --at- Column 2, line 5?, Claim 1, after "means insert -includin'g a yieldabl'y mounted element disposed in said housing-- Signed and sealed this 12th day of December 1972.

(SEAL) Attest:

EDWARD MoFLETCHERfl'Ru ROBERT GOTTSCHALK Attes'ting Officer Commissioner of Patents USCOMM-DC 60376-P69 FORM PO-10S0 (10-69) Us GOVERNMENT PRI'NTING OFFICE: 1969 0-366-334 

1. In a multi-turn variable resistor including a helically formed resistance element, a housing supporting the element about the inner surface thereof, shaft means located within said housing, a slider block carried by said shaft means, electrical conductor means supported by said housing in engagement with spaced positions on said element, a contact member supported by said slider block and adapted to slidably engage the resistance element in response to rotary movement of said shaft and means for releasably securing the slider block relative to said resistance element at a predetermined position of the contact member within the housing.
 2. A variable resistor as set forth in claIm 1 wherein said slider block includes a detent formed in the surface for engagement with said yieldably mounted element to retain the slider block in fixed position relative to the housing.
 3. In a multiturn variable resistor including a helically formed resistance element, a housing supporting the element about its inner surface thereof, shaft means located within said housing, a slider block carried by said shaft, electrical conductor means supported by said housing in engagement with spaced positions on said element, a contact member supported by said slider block and adapted to slidably engage the resistance element in response to rotary movement of said shaft and yieldable means for releasably securing the slider block relative to said resistance element at a predetermined position of the contact member within the housing, said yieldable means being arranged within a radial opening formed in the surface of the housing accommodating the helically formed resistance element so that the end thereof projects into the path of travel of the slider block. 